Contention-based medium access is a traditional medium access scheme in which each Mobile Terminal (MT) acquires channel access by sending data initiation requests in slots that are used by other MTs for the same purpose. Many variants of the contention based medium access schemes, such as ALOHA, CSMA, etc., have been used in numerous wireless technologies, such as IEEE 802.11, LTE, etc., based on its hardware and software capabilities. In this disclosure, we consider a class of wireless systems that uses a medium access scheme with no carrier sense mechanism and whose MAC “super-frame” structure has m CBA slots, where m≥2, that may be used by the MTs to access the medium.
Wireless systems that operate in interference-prone bands due to the presence of other users, such as the ISM band of 902-928 MHz, require physical layer (PHY) algorithms to handle high levels of such interference. While this is highly desired to decode data and other control bursts, PHY level interference mitigation algorithms at the Base Station (BS) may cause detection bias for a set of MTs when decoding CBA bursts. This can be due to several reasons such as receiver signal levels, uplink propagation delay, oscillator and RF characteristics, etc. Hence, fairness of the network is compromised due to resource “hogging” by the biased set of MTs.
One may argue to disable the interference mitigation algorithms operating in the PHY while decoding CBAs to impart bandwidth fairness to the network. But, such algorithms may reduce packet drops due to collisions, and hence increase the network throughput, since a CBA burst from one of the MTs may be decoded while the others may be treated as interference. In the following disclosure, we address the aforementioned issues and introduce a channel access protocol that provides bandwidth fairness to the network while maximizing the network throughput. This protocol intelligently uses the available m CBA slots, where m≥2, to detect collision, and in-turn uses this information to update the “wait” times of the MTs.